This invention relates to novel fuel mixtures for use in engines which use liquid hydrocarbon fuels and to novel processes to prevent phase separation in liquid hydrocarbon fuel and hydrous ethanol mixtures. More particularly, the invention relates to solubilizing ethanol which contains water in liquid hydrocarbon fuels, including gasoline, by means of additives which have no adverse effect on storage, stability, water-shedding or corrosion properties.
The use of commercial ethanol in liquid hydrocarbon fuels such as in gasoline blends commonly referred to as "gasohol", can cause a phase separation problem because of the limited solubility of water/ethanol mixtures in liquid hydrocarbons, particularly in low aromatic content gasolines.
A major cause of this problem is the tendency of ethanol to absorb water. Additionally, industrial grade ethanol commonly used in gasohol contains about 5 percent by weight of water. The water causes the ethanol in liquid hydrocarbon fuel mixtures to separate into a second phase, particularly at low temperatures. This phase separation may also result in corrosion problems and poor combustion performance in the engine.
The literature discloses compositions which solubilize hydrous ethanol in the gasoline. Such compositions include alkyl t-butyl ethers such as methyl t-butyl ether, ethyl t-butyl ether and higher molecular weight distillation bottoms disclosed by U.S. Pat. Nos. 4,207,077 and 4,207,076, respectively.
One of the principal objects of this invention is to provide an improved liquid hydrocarbon fuel composition wherein the liquid hydrocarbon and ethanol components are maintained in a single phase by a phase separation inhibitor.
Another object is to provide a phase separation inhibitor for liquid hydrocarbon fuel and hydrous ethanol mixtures which is effective at very low weight percentages and is economical to use. A further object is to inhibit this separation at temperatures as low as -40.degree. C. to allow the effective use of liquid hydrocarbon fuel and hydrous ethanol mixtures in cold climates such as the northern United States.